
size = int(input("请输入棋盘的大小:"))
for i in range(size):
    for j in range(size):
        if i == 0 and j == 0:
             print( "┏" ,end='' )
        elif i == 0 and j == size - 1:
         print( "┓",end=' ' )
        elif i == size - 1 and j == 0:
         print( "┗ " ,end=' ')
        elif i == size - 1 and j == size- 1 :
         print( "┛",end=' ' )
        elif j== 0:
         print( " ┠" ,end=' ')
        elif i == size - 1:
         print( "┷",end=' ')
        elif j == size - 1:
         print( "┨",end='')
        elif i == 0:
         print("┯",end=' ' )
        else:
         print("┼" ,end=' ' )
print( ' ')   